[jira] [Resolved] (GROOVY-6555) Allow @Immutable classes to validate their properties upon construction

["Paul King (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/GROOVY-6555?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Paul King resolved GROOVY-6555.
-------------------------------
       Resolution: Fixed
         Assignee: Paul King
    Fix Version/s: 2.5.0-beta-3

Now that @Immutable has been made a meta-annotation (see GROOVY-8440), you can now add pre and post closure clauses which are conveyed onto the @TupleConstructor and @MapConstructor annotations.

> Allow @Immutable classes to validate their properties upon construction
> -----------------------------------------------------------------------
>
>                 Key: GROOVY-6555
>                 URL: https://issues.apache.org/jira/browse/GROOVY-6555
>             Project: Groovy
>          Issue Type: Improvement
>          Components: ast builder
>            Reporter: Jan Bols
>            Assignee: Paul King
>            Priority: Major
>             Fix For: 2.5.0-beta-3
>
>
> Currently classes annotated with @Immutable are not allowed to create their own constructor. Instead a map-based and an ordered-based constructor is added by the {{ImmutableASTTransformation}}
> However it would be great if there was some way to *validate* the arguments that are used to populate the immatable object. This would allow the developer to use @Immutable to build [value objects|http://martinfowler.com/bliki/ValueObject.html] allowing them to assert that certain properties are set, certain properties have a certain value, etc...
> A way of implementing this improvement that I can think of is to allow the developer to create his own constructor, relying on the skills of the developer to keep the object immutable
> Another way would be to allow the developer to specify an 'afterPropertiesSet' method in the @Immutable annotation f.e.
> {code:java}
> @Immutable(validationMethod="afterPropertiesSet")
> class MyClass{
>   private afterPropertiesSet(){
>   //some validation of the fields that have been set in the constructor
>   }
> }
> {code}
> This method would be called in the constructors as the last statement.
> Perhaps other solutions exist as well.



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